Field of the Invention
The present invention relates to an ink cartridge containing a plural number of inks, and a printing device using the ink cartridge.
A color printer of the type in which inks of different colors are ejected from a head has prevailed for an output device of a computer. In printing a multi-color image by using three color inks of cyan, magenta and yellow (C, M, Y), some methods are available for the formation of a multi-tone image. One method is employed for the conventional printers. In this method, the size of a dot formed on a sheet of paper by an ink droplet or droplet ejected at once is fixed, and a tone of an image to be printed is expressed in terms of a density of dots (frequency of occurrence of dots per unit area). In another method, a density of an image per unit area is varied by adjusting the diameters of dots printed on the paper. Recently, a fine fabrication technique to fabricate a head for ejecting ink droplets advances, and a density of dots that can be formed within a given length and a range within which the dot diameter may be varied are increased and broadened year by year. However, in the field of printers, a print density (resolution) is at most 300 dpi to 720 dpi, and the diameter of ink droplets is in the order of several tens microns. These figures show that an expression ability of the printer is much inferior to that of a silver-salt photograph (its resolution is several tens dpi on the film).
In a region where an image density is low or a density of dots to be printed is low, dots are sparsely formed (called grained), and this is unpleasant to the eye. To cope with this, a printing device using light and deep color inks and a printing method using the same were proposed. In the proposal, inks of high and low color densities are used for each color, and the ejection of those inks are controlled, whereby a print excellent in tone expression is realized. A recording method for recording a multi-tone image and a device for executing the method are disclosed in Japanese Patent Laid-Open Publication No. Sho. 61-108254. In the publication, a head for forming light and deep color dots for each color is provided. The number of light and deep dots formed within a given dot matrix and an overlapping of those dots are controlled in accordance with density information of an input image, whereby a multi-tone image is recorded.
A plural number of inks must be used for realizing the multi-color printing or multi-tone image printing. Those inks may be supplied from a plural number of ink tanks, respectively. In this case, the amounts of inks left in the tanks must be managed individually, and the piping from the ink tanks to the print head is complicated. To avoid those, the plural number of inks are stored in a single ink cartridge.
In the printing device using the plural number of inks, unsatisfactory study has been made on the proper amounts of the inks contained in the ink cartridge. Recently, to an easy handling, a plural number of inks are stored in a single ink cartridge, and those inks are all replaced with new ones. In this method, when any of the inks is used up, the whole cartridge is replaced with a new one. Thus, unless the amounts of light and deep color inks for each color contained in the ink cartridge are properly determined, the inks other than the ink completely used up must be discarded, and this is wasteful. Accordingly, an object of the present invention is to obtain a proper relationship among the amounts of inks contained in the ink chambers of an ink cartridge.
Where the different amounts of inks are stored in the ink chambers of the ink cartridge, the ink chambers are also different in size, usually, and various problems arise. If the volumes of the ink chambers differ every ink, great difficulties arise in the design of the print head, usually, disposed right under the ink chambers, as well as its printing control. The difficulties will be described in detail. In a printer in which a print head is integrally mounted on a carriage on which an ink cartridge is put, an image is printed while moving the carriage in the widthwise direction of the paper (referred to a main scan direction). It is supposed that at least three ink chambers are arrayed on the ink cartridge in the main scan direction, and printing nozzles are located right under the ink chambers. If the widths (in the main scan direction) of the ink chambers are different with the different volumes of the ink chambers, the nozzle intervals are also different. If a plural number of ink droplets are applied to a position on the paper to form a dot thereat while moving the carriage, it is necessary to individually control the timings of forming the ink droplets for each ink.
In a case where a plural number of inks are stored in a single ink cartridge, when the cartridge is set to the carriage, a plural number of ink supply needles are concurrently inserted into the ink cartridge. This makes it difficult to secure a sufficient sealing at the time of inserting the needles. A plural number of ink supply ports must be provided within a limited space in association with the plural number of ink chambers. Therefore, it is difficult to secure a sufficient deflection of the sealing means, which is mounted on the ink supply ports, in the diameter direction. Accordingly, a slight position shift that may occur at the time of mounting the ink cartridge will deteriorate the sealing performance or damage the ink supply needles. In a case where the different volumes of the ink chambers entails the unequal intervals among the ink supply ports, the sealing problem is more distinguished when comparing with the case where the ink supply ports are equidistantly arrayed. When the intervals among the ink supply ports are different, and as a result, the intervals among the ink supply needles or the intervals among the ink supply ports are varied, strain is frequently concentrated at specific locations.
Accordingly, another object of the present invention is to secure sufficient sealing at the ink supply ports of the ink cartridge including a plural number of ink chambers.
An ink cartridge is invented to achieve at least part of the objects. A printing device using the ink cartridge is invented. The ink cartridge and the printing device of the invention will be described hereunder.
A first ink cartridge of the invention is an ink cartridge containing inks for printer wherein at least three ink chambers for containing inks are formed by partitioning the inner space of the ink cartridge, the volume of one ink chamber being different from the volumes of the remaining ones, and ink supply ports communicatively connected to the ink chambers by way of ink passages are arrayed on the bottom of a main body of the ink cartridge in association with the ink chambers, respectively.
The ink cartridge is provided with at least three ink chambers for containing different inks, and the volume of one ink chamber is different from the volumes of the remaining ones. Ink supply ports communicatively connected to the ink chambers by way of ink passages are arrayed on the bottom of a main body of the ink cartridge in association with the ink chambers, respectively. The ink cartridge has an advantage of an easy ink supply although its structure includes the ink chambers of the different volumes containing a plural number of inks.
The unique feature of the ink supply ports being equidistantly arrayed in a given direction, is very useful in the print head control. Specifically, if the ink supply ports are equidistantly arrayed, the ink ejecting positions are also equidistantly spaced from one another, usually. Accordingly, the control of the timings of ink ejection is also easy.
In the ink cartridge, the ink chambers of three or more are arranged in the direction of transporting the ink cartridge, the difference of the volume of the one ink chamber from those of the remaining ones is realized by the width difference of the one ink chamber, and the given direction in which the ink supply ports are arrayed is the ink cartridge transporting direction. By realizing the difference of the volume of the one ink chamber by the width difference of the one ink chamber, a space required for placing the transported ink cartridge within the printing device can be considerably reduced.
The ink chamber of the different volume, or the volume different from those of the remaining ones, is preferably located at the end of the ink cartridge. By so doing, the ink passages derived from the ink chambers are reduced in length as a whole. The ink chamber of the different volume may contain yellow ink. The yellow ink provides the least graininess when the dots are formed by it. Further, its color density may be set at a desired value, and the volume of the chamber-contained yellow ink may be varied relatively freely.
The ink chambers are five in number and contain magenta ink, light magenta ink whose color density is lower than magenta, cyan ink, light cyan ink whose color density is lower than cyan, and yellow ink, and the ink chamber containing yellow ink may be s located at the trailing end of the series of the ink chambers when viewed in the cartridge transporting direction. Normally, the positions of the ink chambers in the ink cartridge are related to the printing positions of the print head in one-to-one correspondence. Therefore, the ink located at the trailing end is last ejected to form a dot when the ink cartridge is moved. There is a chance that the ink to form dot later spreads into the ink to form a dot early. However, the yellow ink increases a graininess if it spreads and the diameter of a dot formed thereby increases.
The ink chambers are arranged in the order of the cyan ink chamber, light cyan ink chamber, magenta ink chamber, light magenta ink chamber, and yellow ink chamber when viewed in the cartridge transporting direction. By so arranging, if the ink later ejected spreads and a dot formed by it increases its diameter, there is no increase of a graininess of the resultant image.
In the ink cartridge, the ink supply ports includes each a cylindrical fitting part fit to the inner surface of the ink supply port, a thin, cylindrical flexible part extended from the fitting part toward the ink chamber associated therewith while being substantially parallel to the fitting part, and an elastic sealing part being extended upward from the flexible part while being protruded inward, the elastic sealing part liquid tightly receiving an ink supply needle to be inserted into the ink supply port associated therewith. With such a structure, even when a plural number of the ink supply ports are disposed within a limited space, the thin, flexible part extended from the fitting part toward the ink chamber associated therewith while being substantially parallel to the fitting part, operates to thereby ensure a reliable sealing.
A tapered guide surface for guiding the ink supply needle is provided ranging from the bottom-of the fitting part to the flexible part. The unique feature enables the ink cartridge to smoothly be loaded into the carriage. The elastic sealing part is preferably formed protruding from the inner surface of the flexible part through the tapered guide surface for guiding the ink supply needle. When both are formed into a unit, a limited space may be efficiently used.
In the ink cartridge, the ink chambers of three or more are partitioned by partitioning walls, a lid is provided covering the openings of the ink chambers, the chambers having the openings formed in the sides thereof closer to the ink supply ports, a plural number of reinforcing horizontal ribs are raised from the inner surface of the lid while being extended in the longitudinal direction of the ink chambers and located corresponding to the ink chambers, a part of each of the ribs closer to each of the ink supply ports being higher than the remaining part thereof. With such a structure, a strength of the ink cartridge is improved. Therefore, the ink cartridge can be transported without any deformation and any leakage of ink from the fitting parts of the ink supply ports.
The kinds of inks contained in the ink chambers of three or more of the ink cartridge and the amounts (volume) of the chamber-contained inks are correlatively defined as follows: the ink chambers of three or more contain the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn whose lightness values are larger than that of each of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of chamber-contained color inks and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values satisfy the following relation ##EQU1## and the amount of the deepest color ink, chamber-contained, of the n kinds of color inks having the large lightness values is larger than the amount of the deepest color ink, chamber-contained, of the m kinds of color inks.
In the ink cartridge, the total sum of the amounts of the inks having a high lightnes for the same-recording rate is smaller than that of the inks of another hue. When the amount of chamber-contained ink having the highest color density in one hue is compared with the corresponding one in the other hue, the amount of chamber-contained ink of the highest color density of the n kinds of the inks of large lightness values is larger than the amount of chamber-contained ink of the highest color density of the m kinds of light and deep color inks. If the amounts of both the inks are so selected, proper amounts of the chamber-contained inks in the ink cartridge are set up for the amounts of the inks consumed in the ink cartridge of the printing device that prints a multi-tone image. Thus, the amounts of inks stored in the ink chambers are selected as described above, the waste of all the inks in the ink cartridge are reduced for a variation of the amounts of the consumed inks.
The color ink whose lightness value is larger than of the remaining color inks may be yellow ink. A color printing by using inks of three colors, cyan, magenta and yellow may be imagined for such a case. Of those three color inks, the yellow ink is the highest in lightness value. The kinds of the color inks having large values may be reduced in number when comparing to the remaining ones. It is practical that the amount of consumed yellow ink is increased by the reduced number of ink kinds with respect to the amount of deep color ink of the two or more kinds of light and deep color inks. This results in that in the printing device using the inks of the primary colors, cyan, magenta and yellow, the ink cartridge stores the cyan and magenta inks each consisting of at least two kinds of color inks for m kinds of light and deep color inks, and the color ink consisting of only yellow color in for n kinds of color inks.
The amounts of the m kinds of light and deep color inks contained in the ink chambers thereof and the amounts of the n kinds of color inks contained in the ink chambers thereof may be determined in consideration with .gamma.-characteristics of the color inks.
In the ink cartridge of the invention, the ink chambers of three or more contain the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm (the inks become thin in color density in this order) for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn (the inks become thin in color density in this order) whose lightness values are larger than that of each of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of color inks contained in the ink chambers thereof and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values contained in the ink chambers thereof satisfy the following relation EQU vxi&lt;vyi(i: integer between 1 and n).
In the ink cartridge, the amounts of the m kinds of color inks contained in the ink chambers thereof and the amounts of the n kinds of color inks having large lightness values contained in the ink chambers are correlatively defined as just mentioned. To be more specific, let us consider a case where the consumed inks are the inks of the primary colors, cyan, magenta and yellow, and where for each of the cyan and magenta, two kinds of color inks, or light and deep color inks are used, and for the yellow, one kind of color ink is used. In this case, the amount of chamber-contained yellow ink is larger than that of the cyan or magenta ink, as taught by the relation of the amounts of ink-chambered or tank contained inks as stated above. By so selecting the amounts of the ink-chamber contained inks, there is no chance that the amounts of the i-th inks, consumed, of the m kinds of light and deep color inks are each greatly different from the amount of the i-th ink, consumed, of the n kinds of the inks of high lightness. Therefore, proper amounts of the inks are contained in the ink cartridge used by a printing device for printing a multi-tone image. Consequently, the amounts of color inks of different colors and color densities contained in the ink chambers are saved as a whole.
If vyi.ltoreq.1.5.multidot.vxi (i: integer between 1 and n), it never happens that the amount of the i-th ink, consumed, of the n kinds of the inks of high lightness is greatly different from the amounts of the i-th inks, consumed, of the m kinds of light and deep color inks.
Further, in the ink cartridge, the relation may be defined by vyi.ltoreq.1.5.multidot.vxi. In this case, the following relation holds EQU vxi&lt;vyi.ltoreq.1.5.multidot.vxi.
The useless consumption of the inks is reduced as a whole.
Also in this case, in the printing by the primary colors, cyan, magenta and yellow inks may be used. Actually, the ink cartridge stores the cyan and magenta inks each consisting of at least two kinds of color inks for m kinds of light and deep color inks, and the color ink consisting of only yellow color in for n kinds of color inks. The amounts of the m kinds of light and deep color inks contained in the ink chambers thereof and the amounts of the n kinds of color inks contained in the ink chambers thereof may be determined in consideration with .gamma.-characteristics of the color inks.
The ink cartridge may be defined such that the ink chambers of three or more contain the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm (the inks become thin in color density in this order) for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn (the inks become thin in color density in this order) whose lightness values are larger than of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of color inks contained in the ink chambers thereof and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values contained in the ink chambers thereof satisfy the following relations, ##EQU2## and EQU vxi&lt;vyi&lt;vxi+vxi+1 (i: integer between 1 and (n-1)).
In the ink cartridge, the total sum of the amounts of the inks having a high lightness for the same recording rate is smaller than that of the inks of another hue. When comparing the amounts of color inks of color densities with one another, the amount of chamber-contained ink having a color density of the n kinds of color inks having a high lightness is larger than the amounts of the chamber-contained inks having the higher color density of the m kinds of color inks, but is smaller than the total sum of the inks having the lower color density to the amount of ink. To be more specific, let us consider a case where the consumed inks are the inks of the primary colors, cyan, magenta and yellow, and where for each of the cyan and magenta, three kinds of color inks, or light, medium and deep color inks are used, and for the yellow, two kinds of color inks, or light and deep yellow inks, are used. In this case, the total amount of two chamber-contained yellow inks is smaller than that the total amount of three cyan or magenta inks, and the amount of the yellow of high color density is larger than of the magenta or cyan ink of the highest color density, but smaller than the sum of the amount of magenta or cyan ink of the highest color density and the amount of magenta or cyan ink whose color density is next to the former. Further, the amount of yellow ink of low color density is larger than of the cyan or magenta ink of a medium color density, but smaller than the sum of the amount of cyan or magenta ink of the medium color density and the amount of cyan or magenta ink whose color density is next to the former. By so selecting the amounts of both the inks contained in the ink chambers thereof, a great difference is not created between the amounts of the inks stored in the ink cartridge, and proper amounts of the inks are contained in the ink cartridge used by a printing device for printing a multi-tone image. In this case, the unnecessary waste of the inks is further reduced.
In the ink cartridge, the ink chambers are six in number and contain black ink, deep cyan ink, light cyan ink, deep magenta ink, light magenta ink, and yellow ink, and the six ink supply ports provided in association with the six ink chambers are linearly arrayed in the direction of transporting the ink cartridge, the ink supply ports being arrayed in the order of black, deep cyan, light cyan, deep magenta, light magenta, and yellow. This order is determined in consideration with the spreading of inks. The light and deep cyan inks whose graininess is easy to grow are ejected earlier than the remaining one to form dots. As a result, it never happens that the cyan dots are formed in an area formed by another color ink already ejected (the area is still wet), and the dot area grows to increase a graininess.
In addition to the ink cartridge described above, a printing device using the ink cartridge was invented on the basis of the same technical concept as of the ink cartridge. In this respect, it is believed that the combination of the printing device and the ink cartridge satisfies the requirement of the singleness of the invention.
The printing device has a head for ejecting at least two kinds of light and deep color inks and a color ink whose lightness value is larger than the light and deep color inks for the same recording rate, the printing device printing an image in the form of a distribution of dots by the color inks. The printing device comprises:
an ink cartridge including ink chambers for containing inks are respectively formed for the color inks by partitioning the inner space of the ink cartridge, the volume of the ink chamber containing the color ink whose lightness value being larger than of the light and deep color inks for the same recording rate; PA1 input means for inputting a tone signal of an image to be formed; PA1 dot-formation determining means for determining the formation of dots by the m kinds of light and deep color inks for each hue and the ink having the larger lightness value in accordance with input tone signal; and PA1 head drive means for causing the color inks contained in the ink chambers of the ink cartridge to eject from the head by controlling the head in accordance with the result of the dot formation determined by the dot-formation determining means.
The printing device is provided with an ink cartridge having ink chambers containing two or more kinds of color inks of different color densities and color ink whose lightness is higher than of the two or more kinds of color inks for a recording rate. The volume of the ink chamber containing the ink whose lightness is higher than of the two or more kinds of color inks for a recording rate is larger than that of each of the ink chambers containing the remaining inks. If the total amount of consumed ink of higher lightness is smaller than the total amount of two or more kinds of the consumed inks of different color densities, proper amounts of the inks may be left in the ink chambers of the ink cartridge.
In the printing device, the ink cartridge contains the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn whose lightness values are larger than of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of color inks contained in the ink chambers thereof and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values contained in the chambers thereof satisfy the following relation, ##EQU3## and the amount of the deepest color ink, chamber-contained, of the n kinds of color inks having the large lightness values is larger than the amount of the deepest color ink, chamber-contained, of the m kinds of color inks.
In the printing device, the total sum of the amounts of the inks having a high lightness for the same recording rate is smaller than that of the inks of another hue. When the amount of chamber-contained ink having the highest color density in one hue is compared with the corresponding one in the other hue, the amount of chamber-contained ink of the highest color density of the n kinds of the inks of large lightness values is larger than the amount of chamber-contained ink of the highest color density of the m kinds of light and deep color inks. If the amounts of both the inks are so selected, proper amounts of the chamber-contained inks in the ink cartridge are set up with respect to the amounts of the inks consumed by the printing device that prints a multi-tone image.
In the printing device, the ink cartridge contains the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm (the inks become thin in color density in this order) for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn (the inks become thin in color density in this order) whose lightness values are larger than of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of color inks contained in the ink chambers thereof and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values satisfy the following relation EQU vxi&lt;vyi (i: integer between 1 and n).
In the printing device, the amounts of the m kinds of color inks contained in the ink chambers thereof and the amounts of the n kinds of color inks having large lightness values contained in the ink chambers are correlatively defined as just mentioned. To be more specific, let us consider a case where the consumed inks are the inks of the primary colors, cyan, magenta and yellow, and where for each of the cyan and magenta, two kinds of color inks, or light and deep color inks are used, and for the yellow, one kind of color ink is used. In this case, the amount of chamber-contained yellow ink is larger than that of the cyan or magenta ink, as taught by the relation of the amounts of ink-chambered or tank contained inks as stated above. By so selecting the amounts of the ink-chamber contained inks, there is no chance that the amounts of the i-th inks, consumed, of the m kinds of light and deep color inks are each greatly different from the amount of the i-th ink, consumed, of the n kinds of the inks of high lightness. Therefore, proper amounts of the inks are contained in the ink cartridge with respect to the amounts of inks used by a printing device for printing a multi-tone image.
If vyi.ltoreq.1.5.multidot.vxi (i: integer between 1 and n), it never happens that the amount of the i-th ink, consumed, of the n kinds of the inks of high lightness is greatly different from the amounts of the i-th inks, consumed, of the m kinds of light and deep color inks.
In the printing device, the ink cartridge contains the whole or independently at least some of m (m: natural number of 2 or larger) kinds of light and deep color inks X1, X2, . . . , Xm (the inks become thin in color density in this order) for each hue, and n (n: natural number of 1 or larger) kinds of color inks Y1, . . . , Yn (the inks become thin in color density in this order) whose lightness values are larger than of the color inks X1, X2, . . . , Xm for the same recording rate, and the amounts vxk (1.ltoreq.k.ltoreq.m) of the m kinds of color inks contained in the ink chambers thereof and the amounts vyi (1.ltoreq.i.ltoreq.n) of the n kinds of color inks having large lightness values contained in the chambers thereof satisfy the following relations ##EQU4## and EQU vxi&lt;vyi&lt;vxi+vxi+1 (i: integer between 1 and (n-1)).
In the printing device, the total sum of the amounts of the inks having a high lightness for the same recording rate is smaller than that of the inks of another hue. When comparing the amounts of color inks of color densities with one another, the amount of chamber-contained ink having a color density of the n kinds of color inks having a high lightness is larger than the amounts of the chamber-contained inks having the higher color density of the m kinds of color inks, but is smaller than the total sum of the inks having the lower color density to the amount of ink. To be more specific, let us consider a case where consumed inks are the inks of the primary colors, cyan, magenta and yellow, and where for each of the cyan and magenta, three kinds of color inks, or light, medium and deep color inks are used, and for the yellow, two kinds of color inks, or light and deep yellow inks, are used. In this case, the total amount of two chamber-contained yellow inks is smaller than that the total amount of three cyan or magenta inks, and the amount of yellow of high color density is larger than of the magenta or cyan ink of the highest color density, but smaller than the sum of the amount of magenta or cyan ink of the highest color density and the amount of magenta or cyan ink whose color density is next to the former. Further, the amount of yellow ink of low color density is larger than of the cyan or magenta ink of a medium color density, but smaller than the sum of the amount of cyan or magenta ink of the medium color density and the amount of cyan or magenta ink whose color density is next to the former. By so selecting the amounts of both the inks contained in the ink chambers thereof, a great difference is not created between the amounts of the inks stored in the ink cartridge, and proper amounts of the inks are contained in the ink cartridge used by a printing device for printing a multi-tone image.
In the printing device, the printing device is an ink jet printing device, the head is a print head having at least six series of nozzle orifices for independently ejecting ink droplets of black, deep cyan, light cyan, deep magenta, light magenta, and yellow, and control means for causing the print head to eject, in accordance with image signals, ink droplets to form dots each forming one pixel by black ink, deep cyan ink, light cyan ink, deep magenta ink, light magenta ink, and yellow ink in this order.
The amounts of the m kinds of light and deep color inks contained in the ink chambers thereof, and the amounts of the n kinds of color inks contained in the ink chambers thereof are preferably determined in consideration with .gamma.-characteristics of the color inks. A dye concentration (or a lightness of the print) of the ink of each color density is different every printing device. The amounts of the color inks for producing a print of a proper color density are different for each printing device. The .gamma.-correction is used for compensating for those differences. By the .gamma.-correction, the amounts of the color inks are properly set up.